Microbial contamination can have a detrimental effect on any item ordinarily used by consumers or merchants, particularly items used in the medical and food service industries. For example, due to various bacterial outbreaks, there have been at least 200 food poisoning deaths reported in the last 10 years. Moreover, more Americans die from hospital infections each year than from car accidents and homicides combined.
Much of this contamination occurs due to the migration of microorganisms from hard surfaces such as table tops and counter tops to food and to food handlers, thence to food. For example, in the food service industry, contamination commonly occurs on stainless steel surfaces used for food preparation. Various food products are prepared on hard surfaces such as counters, tables, and the like. Bacteria from these products will often collect on such surfaces and, if the surface is not cleansed regularly, can transfer from product to product or from product to the preparer. Numerous studies indicate that cross-contamination occurs as a result of a microorganism coming in contact with a person's hands or with a cleaning cloth and thereafter contaminating other items touched by the cloth or hands, such as equipment or other surfaces.
As a result, wipers that contain anti-microbial agents have been employed to prevent such surface and cloth contamination. Currently, most of these anti-microbial wipers are impregnated with anti-microbial agents that are delivered to the user in a pre-moistened form. However, the disinfecting agent within the wiper can be readily exhausted after only a few washings and rinsings to remove dirt after a period of use. Thus, it is believed that such pre-moistened wipers either inhibit growth on the wipers and/or the hard surfaces cleaned only mildly or may only be used for a limited number of wipes.
Some anti-microbial wipers have been developed that are not pre-moistened. For example, one such anti-microbial wiper that can be delivered in a dry condition is disclosed in U.S. Pat. No. 5,213,884 to Fellows. In the Fellows patent, a wiper is disclosed that contains a hot melt adhesive powder mixed with a chlorine release agent. The adhesive powder and chlorine release agents are incorporated into a tissue suitable for use in the disinfection of hard surfaces.
Although the wiper disclosed by Fellows can be delivered in a dry form, it apparently fails to provide sufficient disinfection over an extended period of time—similar to pre-moistened wipers. After being contacted with water, the release of the anti-microbial agent in such wipers capable of being delivered in a dry state occurs readily without control. This prevents the wiper from sustaining its anti-microbial activity after repeated washings and rinsings.
Another anti-microbial wiper has been marketed by Pal International, Inc. of England under the name WIPEX®. According to the sales literature, this wiper contains poly(hexamethylenebiguanide hydrochloride), alkyldimethybenzyl ammonium chloride, and the disodium salt of ethylenediaminetetraacetic acid (E.D.T.A.). In addition, the wipers include indicator stripes that are stated to fade gradually as the disinfectants are depleted from the wiper. It is believed that U.S. Pat. No. 4,311,479 to Fenn et al. is related to this particular anti-microbial cloth. It is believed, however, that these wipers have not proven to be very effective in reducing certain bacterial activity. Also, it is believed that they might retain only limited anti-microbial activity after several rinses.
In U.S. Pat. No. 4,906,464, Yamamoto et al. describe the preparation of a dispersion of an antibiotic powder, such as a zeolite or an amorphous aluminosilicate whose ion exchange ions have been partially or completely ion-exchanged with antibiotic metal ions and/or ammonium, in a dispersion medium, such as a thermoplastic resin, a polyol, an alcohol, a higher alcohol, a higher fatty acid, or a resin emulsion. The components are mixed at a reduced pressure and at a temperature at which the dispersion medium is a liquid, and where the viscosity of the dispersion is between 2,000 cp. to 200,000 cp. Such dispersions were applied to the surface of nylon, rayon and cotton cloths, and it was shown that the treated cloths apparently had the capacity to kill bacteria within 24 hours in solutions that were sprayed onto the treated cloths. A principal object of the invention was to provide a method for uniformly dispersing antibiotic powder in a dispersing medium such as a resin.
In U.S. Pat. No. 4,938,958, to Niira et aL, an antibiotic resin composition was described as including a resin and an antibiotic zeolite in an amount of from 0.05% to 80% by weight of the composition, where the zeolite contained from 0.1% to 15% by weight of silver and from 0.5% to 15% by weight of ammonium ions. In U.S. Pat. No. 4,938,955, a group from the same assignee disclosed an antibiotic resin composition that included a resin, an antibiotic zeolite like the one just described, and a discoloration inhibitor. An object of the invention was to provide an antibiotic resin composition which does not discolor with time and which exhibits excellent antibiotic effect.
The same type of antibiotic zeolite was incorporated into a transparent self-supporting antibiotic film (U.S. Pat. No. 5,556,699). The film was of an organic polymer and was not over 10 microns in thickness, and included 25 to 100 mg of the antibiotic zeolite per square meter. It was stated that the antibiotic activity was fully effective and complete (100%). An object of the invention was to provide an antibiotic zeolite-containing film having a relatively low content of antibiotic zeolite, which exhibits a satisfactory antibiotic action and is also transparent. Applications were included that showed the lamination of the film to a substrate, such as a resin film, and it was suggested that the laminated film could further be laminated to a layer of resin, metal, or paper to form sheets or other molded products. The molding of such a laminated film to a toothbrush was demonstrated.
In U.S. Pat. No. 4,615,937, to Bouchette, an antimicrobially active wet wiper is described that comprises bonded fibers of a nonwoven web, which are bonded together by a uniformly distributed binder. An antimicrobial agent is bound to the fibers and the binder in a manner that prevents the agent from substantively diffusing from the fibers or the binder, whether the wiper is wet or dry. A purpose of the invention is to prevent the transfer of the anti-microbial agent to a user's skin, where it might leave an irritating residue. Apparently, therefore, any liquid that would be left by the wiper on a wiped surface would be substantially free of the anti-microbial agent.
Thus, it remains that a need currently exists for a more effective wiper that disinfects hard surfaces and inhibits cross-contamination. In particular, a need exists for a wiper that contains an anti-microbial agent that is slowly released when contacted by water, thereby allowing the wiper to provide an anti-microbial solution and to sustain its anti-microbial effectiveness after repeated washing and rinsing operations.